| 摘要 |
The substrate (30) is placed in an enclosure (34) and is heated by direct electromagnetic coupling with an induction winding (38) to enable a temperature gradient to be established within the substrate, so that the substrate has a higher temperature in its portions remote from its exposed surfaces than in the vicinity of its exposed surfaces. A reaction gas constituting a precursor for the material to be infiltrated is admitted into the enclosure, with the formation of the material being favored in those portions of the substrate that are at higher temperature. According to the invention, the substrate is constituted by a fibrous fabric for which the ratio rho r/ rho c of transversal electrical resistivity over longitudinal electrical resistivity is not less than 1.3, and the ratio lambda r/ lambda c of transversal thermal conductivity over longitudinal conductivity is not less than 0.9, and the substrate is situated entirely within the field produced by the induction winding, the substrate and the induction winding occupying positions that are fixed relative to each other. Advantageously, the substrate is constituted by a needled fibrous structure in which the volume ratio of the fibers is not less than 20%.
|
